Segmented Silicon Hairspring Mass Reduction
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Solution Overview
Problem
The challenge is to reduce the mass of a hairspring for a timepiece while maintaining its rigidity, which affects the chronometric performance and isochronism, as existing designs do not efficiently address the mass-rigidity tradeoff.
Innovation Solution
The hairspring features openings distributed along its length, alternating with bridges, which reduces its mass while maintaining equivalent rigidity to a solid hairspring, achieved through micro-fabrication techniques using low-density materials like silicon, diamond, or quartz, and strategically designed bridge and opening configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the mass of the balance spring is reduced to improve isochronism, then the chronometric performance is improved, but the rigidity of the balance spring deteriorates
Solution Approach 1:
The balance spring blade is segmented into multiple openings distributed along its length, creating a series of bridges between the openings. This segmentation reduces the overall mass of the balance spring while the bridges maintain the necessary rigidity, resolving the contradiction between mass reduction and rigidity preservation
Solution Approach 2:
The balance spring incorporates a porous structure with openings distributed along the blade, similar to using porous materials. This allows significant mass reduction while the remaining material structure (bridges) maintains the required mechanical rigidity for proper function
2Stability of the object's composition
If openings are added to reduce mass, then the isochronism improves, but the structural complexity increases
Solution Approach 1:
The balance spring is divided into multiple sections with openings distributed along its length. This segmentation creates a systematic pattern of bridges and openings that can be manufactured using standardized processes, reducing the practical complexity despite the increased structural detail
Solution Approach 2:
The invention modifies the geometric parameters of the balance spring by introducing openings with specific dimensions and distributions. These parameter changes are optimized to achieve the desired isochronism while maintaining manufacturability through controlled variations in opening size, shape, and spacing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly improves the isochronism of the balance-spring regulating member by reducing mass while maintaining rigidity, leading to improved chronometric performance and reduced sensitivity to shocks and thermal variations.
Implementation Method 1
this blade forming turns, of which at least one is provided with a plurality of openings which extend in the direction of the height of the blade and alternate with bridges
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The hairspring has leaf (2) that is provided with specific thickness and height. The leaf is comprised with several apertures (3) extending in height-wise direction and bridges (5) that are provided at apertures in alternate manner. The apertures are distributed over entire length of leaf. Equidistant portions (4) joined to one another are comprised in leaf and separated by apertures. The leaf is made of silicon, quartz and diamond. Core of leaf is made of silicon, and external material of leaf is made of silicon dioxide. An independent claim is included for method of manufacturing hairspring.